The invention relates to a vacuum toilet, as is used, for example, in aircraft and in railway carriages, having a toilet bowl and a vacuum pipeline which opens out into said toilet bowl.
During operation of such vacuum toilets, it is often the case that passengers drop foreign bodies, such as powder compacts, cosmetics articles, combs, spectacles, and the like, into the toilet bowl. Once the vacuum flushing has been initiated, these objects are carried away by suction and may result in blockages in the toilet pipe system, which may adversely affect, or prevent altogether, the continued operation of the vacuum flushing. Such an operational breakdown can often only be rectified by the pipeline system being removed in part in order for the foreign body to be found. This is time-consuming and costly and usually cannot be carried out during the flight or journey, which may result in lengthy and thus disruptive breakdown times. The blockage of the vacuum system by foreign bodies is often all the more serious since it is usually the case that a number of toilets are connected to a single vacuum system, for which reason a number of toilets are put out of action at the same time by a single foreign body.
An object of the invention is to avoid long-term blockages of such a vacuum system by foreign bodies. This object is achieved in that, in the region of the opening of the vacuum pipeline into the toilet bowl, the vacuum pipeline has a cross-sectional narrowing in the form of a foreign-body barrier which projects radially into the line interior. An alternative embodiment of the invention provides an insert pipe part which can be inserted into the vacuum pipeline in the region of the opening, the insert part having a cross-sectional narrowing in the form of a foreign-body barrier which projects radially into the pipe interior.
First of all, the following will better explain and define some of the terms which are essential to an understanding of the invention. The term xe2x80x9cpipelinexe2x80x9d or xe2x80x9cpipe partxe2x80x9d, rather than being restricted to lines of round cross section, covers all conceivable shapes and cross sections (e.g., oval or elliptical) and also covers pipeline arrangements which have different shaping and different dimensions in certain areas. The radial direction is the direction predetermined by the gradient of the flow speed. It is thus oriented perpendicularly to the flow direction and in the direction of the geometrical pipe central axis.
The term xe2x80x9cflowxe2x80x9d relates, in this context, to the flushing fluid which is carried away by suction. The alignment of the foreign-body barrier in the radially inward direction also covers those embodiments which, in addition to the radial component, also have a component in the flow direction or a cross-sectionally tangential component, and which are thus oriented axially or laterally obliquely in the inward direction.
The term xe2x80x9ccross-sectional narrowingxe2x80x9d relates to the diameter of cylindrical bodies which can still just pass freely through the pipeline. For example, with a line diameter of 50 mm, a cross-sectional narrowing of 20% means that cylindrical elements with a diameter of 40 mm can still pass the foreign-body barrier freely, while those with diameters larger than 40 mm remain caught on the foreign-body barrier. The cross-sectional narrowing should be distinguished from a reduction in the cross-sectional area of the pipeline. In the example mentioned, the 20% cross-sectional narrowing could be brought about by a thin inwardly projecting bar of 10 mm in length, although this would barely reduce the free cross-sectional area.
As a result of the cross-sectional narrowing according to the invention, any foreign bodies which have passed into the toilet bowl and, on account of their dimensions, would be sucked into the vacuum system without obstruction, if there were no foreign-body barrier, remain caught on the foreign-body barrier. The foreign-body barrier has to be sufficiently rigid in order to be able to withstand impact and contact pressure exerted by foreign bodies. Arranging the foreign-body barrier in the region of the opening of the vacuum line into the toilet bowl ensures that the foreign bodies are intercepted directly in the region of the opening and, in any case, only a single toilet is affected. Furthermore, this region is easily accessible from the outside, with the result that a foreign body remaining caught on the foreign-body barrier can be removed again very quickly, as a result of which lengthy breakdown times are avoided.
By virtue of a foreign-body barrier which projects radially into the line interior, correct normal operation of the vacuum toilet, in contrast, for example, to a lattice-like barrier, is not obstructed since the feces material is compressible and is carried away past the foreign-body barrier by suction-possibly being compressed in the process. Should, in exceptional cases, the foreign-body barrier be blocked by feces, then, by virtue of the foreign-body barrier being arranged in the region of the opening of the vacuum pipeline, the blockage, in any case, is easily accessible and can be released quickly, for example with the aid of a customarily provided cleaning brush.
Within the context of the invention, the foreign-body barrier is arranged in the region of the opening of the vacuum pipeline, whereby a foreign body which remains caught on the barrier can be removed again, by way of the opening of the vacuum pipeline in the toilet bowl, without the pipeline system having to be dismantled for this purpose. If appropriate, it is also possible for the insert pipe part to be removed, together with the foreign body held fast therein, cleaned and reinserted.
An insert pipe part according to the invention, which is insertable into the vacuum pipeline and has a cross-sectional narrowing in the form of a foreign-body barrier projecting radially into the pipe interior, makes it possible for existing vacuum toilets in aircraft and railway carriages to be retrofitted without additional structural changes to the toilets themselves. In this case, the foreign-body barrier is arranged in the tubular insert part, which can be inserted into the vacuum pipeline in the region of the opening of the same into the toilet bowl. If appropriate, locking may be provided between the insert pipe part and vacuum line.
The foreign-body barrier is preferably configured such that the cross-sectional narrowing brought about by it is more than 10%, preferably more than 20%, more preferably approximately 30%, of the line diameter. The preferred radial narrowing of 30% of the line diameter is based on the fact, on the one hand, that the narrowing has to be of a sufficient size in order to be as effective as possible in keeping out foreign bodies of different sizes and, on the other hand, that the foreign-body barrier must not project radially inwards to too great an extent, since otherwise the risk of blockage during correct operation increases.
In a preferred embodiment, the cross-sectional narrowing which is brought about by the foreign-body barrier is adapted approximately to the smallest clear cross section of the rest of the pipeline system. If there are narrowed locations in the rest of the pipeline system (for example upstream of the feces tank) which could be blocked by cylindrical bodies with a cross-sectional diameter greater than d, then the maximum radial narrowing of the foreign-body barrier is to be accordingly dimensioned such that it cannot have cylinders with diameter d passing it any longer. This means, on the one hand, that objects which can pass the foreign-body barrier can also pass reliably through the rest of the pipeline system; at the same time, the maximum radial narrowing is no larger than necessary, in order for correct operation not to be threatened by blockages. This embodiment is preferred, in particular, when the internal diameter of the vacuum lines decreases, for example in the direction of the feces tank, rather than being constant over the entire pipeline system between the vacuum toilet and feces tank.
The circumferential length of the foreign-body barrier is advantageously 10-50%, preferably 20-40%, more preferably approximately 25%, of the line circumference. Both the circumferential length of the foreign-body barrier and the line circumference relate here to the inner surface of the pipeline wall and/or of the insert pipe part. On the one hand, the circumferential length of the foreign-body barrier should not be selected to be too small, because a small circumferential length means a foreign-body barrier shape which projects inwardly in a relatively pointed manner, which is unfavorable since it increases the risk of blockages. On the other hand, the circumferential length of the foreign-body barrier should not be over-dimensioned and, in particular, it should be not more than 50% of the line circumference. This achieves a situation where, in comparison with a foreign-body barrier formed, for example, over the entire circumference, with the radial narrowing being the same, there is a greater clear cross-sectional area of the line at the location of the foreign-body barrier. This improves the correct operation of the vacuum toilet since, on account of the compressibility of feces material, in particular also the clear cross section, and not just the radial narrowing, is critical for said feces material to pass the foreign-body barrier.
The length of the foreign-body barrier in the flow direction is expediently from 0.2 times the line diameter to equal thereto, preferably approximately half the line diameter. On the one hand, the length of the foreign-body barrier in the flow direction should not be significantly greater than necessary, in order to avoid a pressure gradient being built up over the foreign-body barrier, as a result of which the operation of the feces being carried away by suction during operation could be obstructed. On the other hand, the length should not be too small, since this, in turn, increases the risk of blockages by the associated relatively pointed shape of the foreign-body barrier.
It is preferable for the shape of the foreign-body barrier to facilitate unobstructed passage by feces and tissues, toilet paper, hair and the like during normal operation. The foreign-body barrier does have slightly rounded shapes and is designed, in particular, without corners and edges. xe2x80x9cSlightly roundedxe2x80x9d here means that the radii of curvature of the foreign-body barrier which arise should not be significantly smaller than the pipeline radius. This shaping is advantageous, in particular, in the flow direction, and at that end of the foreign-body barrier which is directed towards the toilet bowl, in order to avoid the formation of protrusions. The preferred shape of the foreign-body barrier is thus a convexity which is oriented radially into the line interior.
The foreign-body barrier may be a separate part which is fixed to the inner pipe wall. However, it is expediently formed by an elastic deformation of the vacuum pipeline and/or of the insert pipe part, the deformation being directed into the line interior, with the result that a separate component and the corresponding fastening are dispensed with. The above-mentioned ideal convexity shape for the foreign-body barrier may be produced particularly straightforwardly by an approximately hemispherical or semi-elliptical counterpart with a radius corresponding approximately to the pipeline radius being pressed, during the production process of the vacuum pipeline and/or of the insert pipe part, into the still plastically deformable material from the outside. The insert pipe part and/or the pipeline thus expediently consist of plastic which allows the corresponding shaping in the production process and is cost-effective in addition.